Incorrect indentation after string literals containing escaped characters

[caudate-julie]

Steps to reproduce:

1. Type string with '\n' in it, press Enter.

a = '\n'

Same for double quotes.

Expected behaviour

a = '\n'
<--- cursor should be here

Actual behaviour

a = '\n'
    <--- cursor is here

Environment data

• VS Code version: 1.30.2
• Extension version (available under the Extensions sidebar): 2019.1.0
• OS and version: Windows 10
• Python version (& distribution if applicable, e.g. Anaconda): 3.7
• Type of virtual environment used: N/A
• Relevant/affected Python packages and their versions: none

Logs

Console:

Starting Jedi Python language engine.

Linter 'pylint' is not installed. Please install it or select another linter".
Error: Module 'pylint' not installed.

[caudate-julie]

I am not familiar with the code, but it may be this string:
https://github.com/Microsoft/vscode-python/blob/c23603c9b7a3dbb805e8339a2d7cf01bb7327b34/src/client/extension.ts#L176
since regex doesn't include end of line.

[jkyeung]

Yeah, this is really annoying. It seems like this was introduced by the "fix" for #3284.

If I had to choose between having line continuation backslashes work properly, or backslash escapes work properly, I would choose backslash escapes in a heartbeat. Some people probably never use backslash for line continuation, while most other people probably use it very sparingly, since PEP 8 encourages implicit line continuation wherever it can be sensibly applied.

And even if you like backslash line continuation, (1) presumably you're not going to have large sections of code riddled with them, since long lines are discouraged anyway, and (2) you have reasonable alternatives for achieving what you need. Whereas there are plenty of situations where you could be using a lot of backslash escapes (strings, regular expressions), and there is no reasonable alternative.

[jkyeung]

I am not familiar with the code, but it may be this string:
https://github.com/Microsoft/vscode-python/blob/c23603c9b7a3dbb805e8339a2d7cf01bb7327b34/src/client/extension.ts#L176
since regex doesn't include end of line.

I'm pretty sure you've hit the nail on the head.

It seems like such a simple and easy fix (see my comment on #5821, which perhaps should gave gone on #3915). If we are wrong about this, and it's actually more complicated, then I wish they would come out and explain why.

[karrtikr]

Prescribed Solution:

• Modify src/client/extension.ts
• Modify the beforeText setting to use the below regex:
• Add tests

There may be a more correct regex to use:

/^(?!\s+\\)[^#\n]+\\$/

See #5821 (comment).

Make sure this does not break the following (from #3284):

a = 1 + \
    <--- indent is here

[ericsnowcurrently]

I've verified that the following indent/dedent properly:

a = '\n'
# cursor here

a = 1 + \
    # cursor here